Rock-drilling machine



3 Sheets-S[heet 1.

(No Model.) I

B. F. BERGH' ROCK DRILLING MACHINE. I No. 308,947. Patented Dec. 9,1884.

N. PETlfls. PhoXoLillwgrnpher. Washin ton. D. c.

(No Model.) 3 Sheets-Sheet 2.

B. P. BERGH.

ROCK DRILLING MACHINE.

No. 308,947. H I. Patented Dec. 9, 1884'.

n, PETER-5. Pnmmho n m. wuhm wn, D. c.

(No Model;

B. F. BERGH.

3 Sheets-Sheet 3.

ROCK DRILLING MACHINE.-

' Patented Dec; 9, 1884 N. PETERs, Pnnwumo n hen wzmln m, D c

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BROR F. BERGH, OF NEYV YORK, N. Y., ASSIGNOR TO EDYVARD J. N. STENT, OFBAYONNE, NEW JERSEY.

ROCK-DRILLING MACHINE.

SPECIFICATION forming part of Letters Patent No. 308,947, dated December9, 1884-.

Application filed June13, 1884. (No model.)

To (all 1072,0727, it may concern:

Be it known that I, Bnon F. BERGII, a citizen of the United States,residing at the city of New York, county and State of New York, haveinvented a new and useful Improvement in Rock-Drilling Machines, ofwhich the following is a specification, reference being had to thedrawings forming part of the same.

The class of machines to which my improvement is applied is that inwhich the movements of hand-drilling are imitated by the combination ina machine of a drill-holder, a hammer, mechanism for vibrating thehammer, and mechanism for feeding the hammerbearing mechanism forward asthe drilling proceeds.

An example of the class of machines to which my improvement is appliedis shown in the application of Henry F.'Parsons and myself, filed May24, 1883, (Serial No. 96,024,) for Letters Patent.

The first part of my invention has for its object the communication ofmotion from the hand-levers to the hammer; and it consists in locatingupon the shaft operated by the handlevers an arm to the extremity ofwhich -a double-ended pawl is pivoted at its center, and combining withthis pawl alink attached to the hammer-arm at one end, and having itsother end so formed and located with reference to the pawl that forevery forward movement of the hand-levers one end of the pawl engageswith and disengages from a notch in the link, while for every backwardmovement of the hand-levers the same operation is performed by theopposite end of the pawl, so that for each excursion of the hand-leversthe hammer will be raised and dropped twice.

The second part of my invention has for its object the connection of thespring with the hammer in such manner that less strain than heretoforewill be brought upon the spring, and it will be less liable to bebroken. It consists in connecting the hammer-arm with the spring byinterposing a stirrup, as here inafter more fully explained.

The third part of my invention has for its object-the lilting andreturning of the drill to the bottom of the bore-hole by a positivemovement; and it consists in communicating an upanddown movement to thedrill-holder from the hand-levers by a lever which receives a positivemotion both upward and downward.

The fourth part of my invention has for its object so feeding the frameof the machine as 5 5 to have its position upon the guide bars alwayslocked when the feed is not required, but always unlocked just previousto the in stant when any feed is required, so that the force of thehammer can never fall upon the 6') connections between the frame of themachine and the guide-rods. It consists in interposing between thedrill-holder or plunger and the rack upon the guide-rod a carriagereciprocating in the frame, and provided witha tooth to engage with therack, and having its horizontal reciprocating movement governed bymechanism set in motion by a projection con.- nected with thedrillholder or plunger, and its vertical reciprocating movement governedby a rod or lifter receiving motion from the hand-levers.

Myinvention also consists in the details of construction.

I will now proceed to describe what I understand to be the best form ofmachine for embodying my invention, referring to the drawings.

Figure 1 is a side view of my machine with the guide-rods and thehandlevers removed. Fig. 2 is a front view of my machine containing thesockets for the hand-levers, but not containing the guide-rods. Fig. 3is a top View of my machine with the hammer-head and part of thehammer-arm removed. Fig. at is a cross-section through the line 4. 4,Figs.

1 and 3. Fig. 5 shows a side view of the parts surrounding the plungeror drill-holder. Fig.

6 is a longitudinal section through the line 6 6, Fig. 5. Fig. 7 is across-section through 0 the line 7 7, Fig.- 5. Fig. 8 is a cross-sectionthrough the line 8 S, Fig. 5. Fig. 9 is a side view of the plunger ordrill-holder, with the parts immediately surrounding it in section. Fig.10 is a front view of the mechanism con- 5 necting the hand-lever shaftwith the hammer-arm. Fig. 11 is a side view of the same in sectionthrough the line 11, showing the position of the parts when the hammeris raised. Fig. 12 is the same, not in section, showing the position ofthe parts when the hammer has fallen. Fig.'13 shows in detail the formofthe hole or recess in the carriage l the reaction of the spring on thehammer into 6 for the pin 8.

First,as to the mechanism for creating and controlling the motions ofthe hammer: a is the shaft of the hand-lever, having its bearings in theframe of the machine. bis the frame of the machine. It consists at itsforward end, as shown in cross-section at Fig. 7,

of a vertical drill-holder or plunger on its forward side. Rearward fromthis barrel the frame extends in two parallel branches,which unite attheir rear extremities at the point where the hammer-arm is pivoted. Theoperating mechanism is mainly contained between and protected by thesetwo branches of the frame, and upon the shaft a is fixed a vibratingarm, 0, extending in the position shown in the drawings. This vibratingarm is forked toward its extremity, and within this fork is placed adouble-ended pawl, d, which issecured within the fork by a pivot, c. Theform of this pawl and the position in which it is end of the link arebroadened toward their extremities, so as to bear upon the peripheriesof the disks ff, and are thuskept always equidistant from the center ofthe shaft a. It will be seen that the forked link h is thus free to moveforward and back upon the disks f f, but is prevented by those disksfrom any lateral movement at its forward extremity. Within each branchof the forked link h, and between the portions of the branch bearingupon the disks ff, is cut a slot, 1' 2i. WVithin each of these slots isintroduced a stop or projecting flange, jj. The length of the pawl dfrom the pivot e to' its point, and also the curve of the pawl cl, areregulated substantially as shown in Fig. 11that is to say, they are soregulated that when one extremity of the pawl engages with one of thestops j orj the other extremity of the pawl will not be e11- gaged witheither of said stops, and the pawl is given play enough around its pivote to al: ternately bring first one extremity and then the other of thepawl into gear with the stops j or j. In Fig. l the hammer is shown asdown and the forked link h in its most forward'position. The right-handextremity of the pawl is shown in engagement with the stopj by dottedlines. By rotation of the shaft a in the direction of the arrow, thehammer is raised, the link h is pressed backward, and the pawl (Z isrotated to the position shown in Fig. 11, where the stop j is just atthe point of dropping off the extremity of the pawl d. In Fig. 12 theforked link h, having been released from the pawl d, has been thrownforward by the position shown, and the forward 'motion of the forkedlink h has caused the corner of the stop j to impinge against theoutside of the pawl d, and, owing to the cam-formed surface of thelatter, to rotate the pawl (1 around the pivot e and throw itsright-hand extremity inward, while its left-hand extremity is thrownoutward ready to engage with the stopj, as shown in Fig. 12. The partsare so timed that this change takes place j ust before the operatormoves his hand-levers, so as to give the shaft rotation in the oppositedirection to the arrow, and when the shaft is given this rotation thesame mode of operation takes place between the left-hand extremity ofthepawl (Z and the stopj, as has been described as taking place between thecorresponding parts on the other side. The stopsj jare made of steel,and are made separate from the forked link h, so that when worn they maybe cheaply and readily replaced. k

is the spring for actuating the hammer, which is I placed between thebranches of the frame, and is secured between the set-screw Z and thepin m. Its free end is curved, as-shown in dottedlines in Fig. 1, andrests upon a pin at the end of a stirrup, n. The upper end of thisstirrup is also curved or hooked in form, and rests upon the pin a,attached to the hammer-arm g on the same side of the pivot g as the linkh is attached. The mode of operation of the hammer-actuating mechanismis then as follows: hen the hammer is down, the spring his leastcompressed, and the link it is in its forward po sition. The operator,through the medium of the hand-lever, rotates the shaft a first in onedirection and then in the other. As the shaft is rotated in onedirection the right-hand extremity of the pawl d, engaging with the stopj, pushes the link it backward until the stopj and the extremity of thepawl d have passed so far around that they slip by each other. The actof pushingthe link lrbackward, however, has in the meantime raised thehammer 9 and compressed the spring 70 through the medium of the stirrupn, and as the stop j slips by the extremity of the pawl dthe spring itreacts upon the hammer and forces both it and the forked link Itforward. The operator then, through the medium of the hand-levers,rotates the shaft or in the opposite direction, and then the left-handextremity of the pawl d repeats the operation which had just beenperformed by the right-hand extremity there of. In this manner for eachforward and each backward movement of the hand-levers the coast? a thatit will not turn thereon and the other se- 1 since the levers n a are attheir forward ends cured to the hand-levcr, and these disks having upontheir faces teeth to engage with each other, so as to prevent the disksturning upon one another. The teeth are held in engage ment by a spiralspring located upon the shaft, which presses the disk attached to thehandlever toward the disk attached to the shaft.

- The operator may force the disks apart against cured in place upon thetop of the plunger o spring 8, resting on thecollar 1".

by a nut-,p. The plunger 0 projects down ward through the barrel formedby the frame of the machine b, but interposed between said barrel andthe plunger is a sleeve, q. Below the sleeve q a collar, r, isinterposed between the plunger 0 and the barrel Z), and this collar r ispinned fast to the-plunger. A stiff spiral spring, 8, is placed aroundthe plunger between the collar 1' and the sleeve q. The sleeve (1 isthus held downward by the nut p against the upward pressure of thespiral At its top the sleeve q is provided on opposite sides of theplunger with projecting pins ft, and each pin is surrounded by a.friction-roller. u a are two levers of the form shown clearly in Fig. 1.The forward end of each of these levers is provided with a longitudinalslot so placed and formed as to fit the friction-rollers on the pins 1;t. Toward its rear extremity each ofthe levers a a is provided with acurved slot, r '11, and into each of these slots projects a pin, to 10,attached to the frame b, and provided at its outer extremity with africtionroller interposed between it and the sides of the slots r. i

ax are arms fixed with relation to the shaft a so as to turn with it,and each provided with an inward-projecting pin, y g which pass throughthe levers a it. By the arrangement above described the motion of theshalt a in the direction of the arrow, Fig. 1., will throw the arms a: aforward, and their motion, being comm unieated through the pins y willthrow the levers u a" forward. The pins '6 t and their friction-rollersadvance from the forward end toward the rear of the slots in the leversa a,- but at the same time that these levers n a are thrown forward theform of the slots U r at their rear extremity wi.l first cause that rearextremity to be lowered, and then raised again, thus vibrating thelevers n. u. about the pins y y as centers and raising and lowering theforward ends of the levers simultaneously. When the shaft a is rotatedin the opposite direction, the same action is repeated, and for eachforward and each backward movement of the shaft a the forward ends ofthe levers n c are raised and lowered simultaneously; but

engaged with the pins t t, attached to the sleeve q, as alreadydescribed, that sleeve will be raised and lowered in the same manner,and will in turn convey its upward and downward movements to the plunger0. Thus the distance that the plunger 0 is moved upwardalwayscorresponds exactly with the motion of the levers n u, because theupper edge of the sleeve 1 rests directly against the lower edge of thenut 1). 0n the other hand, provision is made, by intcrposing a stiffspiral spring, 8, between the sleeve (1 and the collar 1', so that thedownward stroke which the plunger 0 receives from the levers a a may bevery slightly elastic. This elasticity is provided for the followingreason: The feed of the frame of the machine is intermittent, and eachtime it feeds it moves forward about one-quarter inch. Be

tween the intervals of feed the drill advances into the rock at eachblow of the hammer, and thus the plunger or drill-holder will, whileresting at the bottom of the borehole, at times be farther forward inthe barrel of the frame than at others. The "reciprocation of theplunger or drill-holder in the barrel of the frame must therefore begreater at some times than at others, while the reciprocation of theforward ends of the levers u is always the same. To provide for thisdifference, and at the same time to insure that the drill shall alwayshe returned to the bottom of the bore hole, is the object of the springa, which will be compressed when the downward motion of the forward endsof the levers a a is greater than the downward motion of the plunger ordrill-holder 0.

Third, as to the mechanism for turning the drill: Upon the periphery ofthe nut 19 are placed ratchet-treih p. 011 the top of the lever n ispivoted a pushingpawl, e, and on the top of the lever n is pivoted apulling pawl, 2. These two pawls are pivoted at the extrei'niliesopposite to their teeth, and their toothed ends are held together by aspiral spring, 2, as clearly shown in Fig. 3. It will be seen that byeach movement of the levers n a backward the pawl will engage with theratchet and rotate the drill-holder or plunger in the direction of thearrow, Fig. 3, and that with each forward movement of the levers a u thepawl will engage with the ratchet and move the drill-holder in the samedirection. Thus the drillholder will be rotated the dstance between theteeth of the ratchet for every backward and every forward movement ofthe levers u a. The parts already described for lifting the drill andthe relationship between the teeth of these pawls and ratchet are sotimed that the drill will be lifted from the bottom of the drillholderbefore it is turned. Thus breakage and wear of the edge of the drillwhich would result from turning it be fore lifting it are prevented.

Fourth, as to the mechanism for feeding the machine forward so as tokeep pace with'the advance of the drill into the rock: The frame of themachine I) is provided on either side, the carriage is free to move upand down to nearly opposite the barrel, with suitable recesses at 3 3 33, to fit upon the guide-rods 4 4, which are arranged similarly to thoseshown in the application of Henry F. Parsons and myself, before referredto. Upon one of these guide-rods, as the one located at the left-handside of the drill-holder, is secured a rack, 5.

6 is a carriage, which is so secured that when not locked it mayreciprocate either vertically or horizontally, it being held in positionby slotted connections with the rod 7 and pin 11. The reciprocatingcarriage 6 is provided with a tooth, which takes into the rack 5. Thesleeve g, at its upper end, is provided with a backwardly -projectinglug, into which is screwed a downwardly extending rod, 7. This rodprojects downwardly through the frame b, in which it has its bearings,as shown in Fig. 6, but in which it is free to reciprocate up and down.This rod 7 passes through a horizontal slot in the carriage 6, asindicated in Fig. 8, andjustbelow the point where it is encircled by thecarriage the rod is provided with a shoulder, as shown in Figs. 6 and 1.This shoulderis so located that when the carriage is in the positionshown in Fig. 6 the rod 7, which is reciprocated up and down with thesleeve q, may move without affecting the carriage 6, but so thatwheneversaid carriage falls below the position shown in Fig. 6 it willbe struck by the shoulder referred to on the upward stroke of the rod 7.The carriage 6 has a downward prolongation, as shown in Fig. 6, andthrough this prolongation is cut a hole of the form shown in Figs. 13and '6. This hole is made up of two portionsfirst, a slotted portionextending all the way through the carriage 6 in a horizontal direction,and, second, an enlarged circular portion which extends a part of theway through from the rear of the said carriage. Into this hole is fitteda pin, 8, which is also made up of two portionsiirst, a circular portionwhich is just long enough to extend through the slotted hole in thecarriage, and, second, an e11- larged circular portion which is of thesame size as the enlarged circular hole in the carriage, and whichprojects backward from the carriage through a lug, 9, 011. the frame ofthe machine and beyond the said lug, and which bears at its rear endagainst the spring 10, secured to the frame of the machine, as shown inthe various figures. lVhen the carriage 6 is in its highest position, asshown in Fig. 6, the enlarged part of this pin fits into the enlargementof the hole in the carriage 6, already referred to, and since thisenlargement ofthe hole is circular and not slotted, thecarriage can moveneither upward nor downward upon the pin 8, but is secured by that pin,and locked firmly to the frame of the machine, through which, as abovestated, the pin passes. When, however, the pin is forced backwardagainst the action of the spring 10 such a distance that the enlargedportion of the pin is thrown out of the hole in the carriage 6, then theextent provided for by the slotted form of the smaller portion of thehole in the carriage 6. The lower extension of the carriage 6, afterpassing by the point where it is perforated by the pin 8, extendsdownward and receives in a vertical slot near its lower extremity thepin 11, and below that pin is provided a spiral spring, 12, which tendsto press the carriage 6 downwardly. 13 isa lever pivoted on the pin 11and provided with three arms, 14, 15, and 16. The arm 15 projectshorizontally in such position below the collar 1 on the plunger ordrill-holder 0 that when ever said plunger or drill-holder has advancedto a point where it is desirable for the frame of the machine to be fedforward the further advance of said plunger or drill-holder will causethe collar- 1" to press the arm 15 downwardly. Thearm 14 extendsupwardly along the face of the carriage 6 and opposite to the end of thepin 8, projecting through said carriage, as shown in Fig. 6. WVhen thecarriage 6is locked to the frame by the pin 8, as already described, thearm 14 will rest against the end of the pin 8; but when the collar 1" onthe plunger has advanced, as already described, so far as to press thearm 15 downward, the arm 14: will thereby be moved so as to press thepin 8 inward against the action of the spring 10 until the enlargedportion of said pin is entirely clearof the holein the carriage 6, asindicated in dotted lines in Fig. 2; but the parts are so adjusted thatthe motion of the arms 15 and 14 do not stop until the arm 14 has notonly pressed the pin 8 backward,as described, but also until the arm 14has pressed the carriage 6 back into the position shown in Fig. 2, wherethe tooth of the carriage 6 is disengaged from the teeth of the rack 5.The spring 12 now comes into play and forces the carriage 6 downward thedistance between two teeth of the rack 5, and so that the tooth on thecarriage is in the proper position to engage between the two teeth ofthe rack next below the two with which it had been previously engaged,or in the position shown in Fig. 2. The plunger or drill-holder is nowlifted,and with it the collar 1'', so as to release the arm 15 andpermit the spring 10, acting ,ence to the pin for the enlargement of thepin to enter the enlargement of the holein the carriage. As, however,the drill is lifted the .shoulder on the rod 7 comes in contact with thecarriage 6. Now, the carriage is prevented from moving upward by theengagement of its tooth with the rack, and consequently the frame of themachine is slid downward on the guide-rods 4 a distance correspondingwith the distance between the teeth of the rack 5. This changes therelative position of the carriage 6 and the other IIO parts from thatshown in Fig. 2 to that shown in Fig. 6, and the enlarged part of thepin 8 is then pressed forward by spring 10 into the enlargement of thehole in carriage 6, and the parts are firmly locked again, and continueso until the drill has advanced far enough to make another feednecessary, when the same operations are repeated. The collar r is soplaced on the plunger that it will strike the arm and force the tooth oncarriage 6 out of engagement with the rack before the hammer has driventhe plunger far enough for the force of the hammer to strike the frame.Thus the connection between the frame and the rack 5 can never bestrained or broken by any strain from the blow of the hammer. The collar1' should always be so placed on the plunger that the feed will takeplace sufficiently often to always place the point of the drill on thebottom of the bore-hole a little before the forward ends of the levers aa? have completed their downward strokes, so that the blow of the hammershall never be communicated to the levers a a.

Fifth, as to mechanism whereby the operator may unlock the frame of themachine from the rack 5 to move the frame back on the guides orotherwise adjust the machine: The arm 16 of the lever 13 rests on a pin,17, which may be turned by the thumb-handle 18. A recess is cut on oneside of the pin 17, which may be i brought opposite the arm 16 byturning the pin. When the machine is working, the re cess is oppositethe arm 16, and in that condition the pin 17 does not affect thedescribed operation of the lever 13. \Vhen, however, the pin 17 isturned, it raises the arm 16, and, throwing the arm 14 forward, forcesthe pin 8 backward and disengage's the tooth on carriage 6 from therack. This the operator can do at any time by turning the thumb-handle18, and he can then move the frame in any way he pleases on theguide-rods 4. When in the operation already described the tooth of'the'carriage 6 is disengaged from the rack 5, it is necessary thatthere be something to prevent the frame from dropping on the guides 4 ofits own weight. This is effected by a clamping device 011 the pin 17,which presses against the guide-rod 4 to produce sufficient friction tohold the frame of the machine up against its own weight. 20 is aspring-plate attached to the frame I), and having its free end extendout opposite to the guide-rod 4. A friction-block, 21, which may befaced with leather, is interposed between the free end of thespring-plate 20 and the guide-rod 4. The pin or spindle 17 projectsthrough a hole in the spring-plate 20, to which it is secured. Betweenthe head 22 of the pin 17 and the adjacent face of the frame Z) areformed cam or V shaped surfaces, so that when the pin or spin die 17 isturned in the position shown in the drawings the pin will be retractedto the extent provided for by the cam-surfaces, so as to press thespring-plate 20 and create friction between the block 21 and theguide-rod 4C.

This is the position of the pin 17 when the described automatic feedingdevices are in operation, and it will thus be seen that the frame of themachine will be held up against its own weight, and only be fed forwardby the mechanism provided for that purpose. \Vhen, however, the handle18 is turned so as to throw the carriage 6 out of gear with the rack 5,the form of the cam-surfaces is such as to permit the spring-plate 20 todraw the pin 17 inward and break the friction-connection between thefriction-block 21 and the guide-rod, so that the frame moves freely uponthe guide rod.

I do not wish to be understood that all of the parts orcombinationsdescribed are necessary, or that Iintend to'limit myself tocom binations containing them all.

I am aware that parts of my invention, which I have described may beused without others, and that in my description of each part-I havedescribed devices which in some cases might be omitted and in many casesmight be replaced by other devices for the same purpose withoutdeparting from the es sential principles of my invention.

I am aware that the striking-pin and the de vice for securing the sameare old, as claimed in my previous application No. 96,024, and I do notherein claim anything claimed therein.

I claim-- 1. The combination, with a drill-holder, of a hammer foractuating said drill-holder, a bifurcated link connected with saidhammer, a hand-lever, and a doubleended pawl actuated by the hand-leverfor imparting motion to the link, substantially as described.

2. The combination, with a drill-holder, of a hammer for actuating saiddrill-holder, a bifurcated link connected with said hammer, ahand-lever, a double-ended pawl actuated by the hand-lever for impartingmot-ion to the link, a lever or levers connected with the h andlever,whereby a positive up-and-down motion is imparted to the drill, aratchet on the drill-holder, and a pawl or pawls actuated by the saidlast-mentioned lever or levers for imparting a rotary motion to thedrill, substan tially as described. V

3. In combination, the drill-holder, the collar rigidly secured thereto,the sleeve, the spring interposed between the collar and the sleeve/thedrill-lifting lever or levers provided with slotted connections with thesleeve and frame, the drill-turning pawl or pawls, the saiddrill-lifting and drill-turning devices being operated by one set oflevers, substantially as described.

at. The combination, with a drill-holder, of a nut bearing a ratchetthereon, a lever or levers bearing a pawl or pawls for engaging withsaid ratchet, a sleeve fitting loosely about said drill-holder andhaving a positive connection with said lever or levers, a collar rigidlyaffixed to said drill-holder, a spring between the sleeve and thecollar, and a hand-lever for imparting motion to said lever or levers,the whole being so arranged and combined that the lever or levers may beoperated to raise and lower the drill-holder and to rotate the same,substantially as described.

5. The combination, with a sliding frame which carries the drill and itsoperating mechanism, of ah ammer, a drill-holder, a collar rigidlyaffixed thereto, a lever having one arm extended in the line of movementof said collar, a carriage having a lateral movement in the slidingframe, and a fixed rack with which said carriage is normally engaged,the whole being so arranged and combined that the forward movement ofthe drill-holder will operate the lever to cause the carriage to becomedisengaged from said rack, substantially as described.

6. The combination, with the sliding frame which carries the drill andits operating mechanism, of a hammer, a drill-holder, acollar on saiddrill-holder, a lever having one arm extended in line with the movementof said collar, a carriage having a lateral movement in the frame, afixed rack with which said carriage is normally engaged, a 'pin engagingsaid carriage, and a spring for holding said carriage in engagement withthe rack, all being arranged substantially as described, whereby saidpin may be moved out of e11- gagement with the carriage and the carriagemay be moved out of engagement with the rack, substantially asdescribed. I

7. The combination, with the-sliding frame which carries the drill andits operating mechanism, of a fixed rack with which engages a carriageon said slidingframe, a rod, 7, connected with the reciprocatingdrill-holder and bearing a stop to engage with said carriage, andmechanism, substantially as described, for imparting a vertical andlateral movement to said carriage relatively to the sliding frame, allsubstantially as described.

8. The combination, with a sliding frame which carries the drill and itsoperating mechanism, of a fixed rack, a carriage on said frame engagingnormally with said rack, a lever adapted to move said carriage out ofengagement with said rack, a cam on the sliding frame bearing againstsaid lever, and means, substantially as described, for operating saidcam, substantially as described.

9. The combination, with the sliding frame which carries the drill andits operating mechanism, of ahammer, a drill-holder, a collar on saiddrill-holder, a carriage having a lateral movement in the frame, a fixedrack with which said carriage is normally in engagement, a leveractuated by the drill-holder for imparting motion to the carriage inabackward direction, a spring for imparting motion to said carriage in adownward direction, and another spring for imparting motion to saidcarriage in a forward direction, substantially as described.

, 10. The combination, with the frame b, which carries the drill and itsoperating mechanism, of the guide-rods 4, the friction-blocks 21, attached to the spring-plate 20,whichis secured to the frame I), the pin17, hearing against the spring-plate, and the thumb-piece l8 and cam 22on said pin, the mechanism being adapted to force the friction-blockinto contact with said guide-rods to support the frame, substantially asdescribed.

BROR F. BERGH.

Witnesses:

T. J. KEANE, D. H. DRISCOLL.

